A novel thermo‐mechanically coupled material model for glass above the glass transition temperature

Abstract

AbstractThin glass products have a giant field of application in several engineering branches such as for example, electronics, medical equipment, and the automotive industry. The non‐isothermal glass molding is a novel replicative glass processing technology enabling the realization of a cost‐efficient production of surface shapes with high accuracy and complexity. However, the application of this technology to thin glass production still causes shape distortions, cracks, and surface defects in molded parts. Therefore, these glass‐forming processes should be simulated by means of the combination of experimental investigation and mechanical modeling of glass above the glass transition temperature at finite strains. Previous experimental studies have shown that the Maxwell model is a reasonable approach for an appropriate prediction of the material behavior. Based on this viscoelastic formulation, a thermo‐mechanically consistent material law is used enabling the prediction of rheological effects noticed during the experiments. More specifically, the relaxation behavior can be described by a stress‐dependent relaxation time and the dissipation generated is considered as well. Furthermore, isothermal uniaxial compression tests above the glass transition temperature are conducted for different strain rates and temperatures within the experimental investigation. Combining the experimental data with the simulation, a multi‐curve‐fitting leads to suitable material parameters with respect to distinct temperatures employing a nonlinear optimization.